Drosophila Rab23 Is Involved in the Regulation of the Number and Planar Polarization of the Adult Cuticular Hairs by ProQuest

The planar coordination of cellular polarization is an important, yet not well-understood aspect of animal development. In a screen for genes regulating planar cell polarization in Drosophila, we identified Rab23, encoding a putative vesicular trafficking protein. Mutations in the Drosophila Rab23 ortholog result in abnormal trichome orientation and the formation of multiple hairs on the wing, leg, and abdomen. We show that Rab23 is required for hexagonal packing of the wing cells. We found that Rab23 is able to associate with the proximally accumulated Prickle protein, although Rab23 itself does not seem to display a polarized subcellular distribution in wing cells, and it appears to play a relatively subtle role in cortical polarization of the polarity proteins. The absence of Rab23 leads to increased actin accumulation in the subapical region of the pupal wing cells that fail to restrict prehair initiation to a single site. Rab23 acts as a dominant enhancer of the weak multiple hair phenotype exhibited by the core polarity mutations, whereas the Rab23 homozygous mutant phenotype is sensitive to the gene dose of the planar polarity effector genes. Together, our data suggest that Rab23 contributes to the mechanism that inhibits hair formation at positions outside of the distal vertex by activating the planar polarity effector system. [PUBLICATION ABSTRACT]

Copyright Ó 2010 by the Genetics Society of America
DOI: 10.1534/genetics.109.112060
Drosophila Rab23 Is Involved in the Regulation of the Number and Planar
Polarization of the Adult Cuticular Hairs
´
Csilla Pataki,*,1 Tamas Matusek,*,1 Eva Kurucz,* Istvan Ando,* Andreas Jenny†
´ ´ ´
and Jozsef Mihaly*,2
´ ´
*Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged 6726, Hungary and †Department of
Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461
Manuscript received November 13, 2009
Accepted for publication January 27, 2010
ABSTRACT
The planar coordination of cellular polarization is an important, yet not well-understood aspect of
animal development. In a screen for genes regulating planar cell polarization in Drosophila, we identiﬁed
Rab23, encoding a putative vesicular trafﬁcking protein. Mutations in the Drosophila Rab23 ortholog
result in abnormal trichome orientation and the formation of multiple hairs on the wing, leg, and
abdomen. We show that Rab23 is required for hexagonal packing of the wing cells. We found that Rab23 is
able to associate with the proximally accumulated Prickle protein, although Rab23 itself does not seem to
display a polarized subcellular distribution in wing cells, and it appears to play a relatively subtle role in
cortical polarization of the polarity proteins. The absence of Rab23 leads to increased actin accumulation
in the subapical region of the pupal wing cells that fail to restrict prehair initiation to a single site. Rab23
acts as a dominant enhancer of the weak multiple hair phenotype exhibited by the core polarity
mutations, whereas the Rab23 homozygous mutant phenotype is sensitive to the gene dose of the planar
polarity effector genes. Together, our data suggest that Rab23 contributes to the mechanism that inhibits
hair formation at positions outside of the distal vertex by activating the planar polarity effector system.
T HE formation of properly differentiated organs
often requires the planar coordination of cell
polarization within tissues, a feature referred to as
Mutations in PCP genes result in abnormal wing hair
polarity patterns and wing hair number (Gubb and
Garcia-Bellido 1982; Wong and Adler 1993). On the
planar cell polarity (PCP) or tissue polarity. Although basis of their cellular phenotypes (i.e., prehair initiation
planar polarity is evident in many vertebrate tissues site and number of hairs per cell), initial studies placed
(such as ﬁsh scales, bird feathers, and cochlear epi- PCP genes into three groups: the ﬁrst group (often
thelium) and it has recently been shown that PCP called the core group) includes frizzled ( fz), dishevelled
regulation is highly conserved throughout the animal (dsh), starry night (stan) (also known as ﬂamingo), Van
kingdom (Strutt 2003; Fanto and McNeill 2004; Gogh (Vang) (also known as strabismus), prickle (pk), and
Seifert and Mlodzik 2007; Simons and Mlodzik diego (dgo); the second group consists of inturned (in),
2008), such polarization patterns are best studied in the fuzzy (fy), and fritz ( frtz) (referred to as planar polarity
fruitﬂy, Drosophila melanogaster. PCP in ﬂies is manifest in effectors or In group); whereas the third group includes
the mirror-image arrangement of ommatidia in the eye, multiple wing hairs (mwh) (Wong and Adler 1993).
in the adult cuticle, which is decorated with parallel Double mutant analysis demonstrated that these phe-
arrays of hairs and sensory bristles,

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